Ion channels (Part II)



Ion channels translate ionic fluxes across cell membrane into electrical impulses. Potassium channels (KCh) are subdivided to voltage-gated KCh and calcium-dependent KCh. The latter are subdivided into high- (BK, LKCa), intermediate- and small-conductance KCh (human SK1, rat SK2, SKCa). MthK is a calcium-dependent potassium channel from Methanobacterium thermoautrophicum. MscL and MscS are large- and small-conductance mechanosensitive channels which protect bacteria from osmotic shock by allowing ions to flow across the cell membrane. Voltage-Dependent Calcium Channels (VDCC) allow Ca to enter the cell resulting in muscle contraction, neuron excitation or hormone release. VDCC are composed of several subunits and are named as a Cav gene product. The human annexin V molecule serves as a calcium channel. There are also Voltage-Dependent Anion Channels (VDAC). Chloride ion channels (ClCh) are involved in maintaining pH, volume homeostasis and more. Ligand-Gated Ion Channels (LGIC) open or close when binding a ligand like a neurotransmitter. The Cyclic Nucleotide-Gated channel (CNGC) conduct cations upon binding of cAMP or cGMP. The Acid-Sensitive channels (ASC) conduct cations upon binding of acid. The images at the left and at the right correspond to one representative ion channel structure, i.e. the crystal structure of NaK Channel from Bacillus cereus (1qrq).

Potassium channel
See: Potassium Channels

BK channel
3mt5 – hBK cytoplasmic domain

1jo6 – BK beta 2 N- terminal KCNMB2 encoded LKCa - NMR

MthK
1kxd – MthK RCK domain+Cd - Methanobacterium thermoautrophicum

2ogu, 2fy8, 2aej, 2aem, 1lnq - MthK RCK domain

2aef - MthK RCK domain+Ca

Calcium channel
3bxx – rCav2.1 alpha 1A subunit+calmodulin

3bxl - rCav2.3 alpha 1E subunit+calmodulin

2f3y, 2f3z, 2be6 – hCav1.2 alpha 1C subunit+calmodulin

1t0h – rVDCC beta 2A subunit

1t0j – rVDCC beta 2A+alpha 1C

1vyt - rVDCC beta 3+alpha 1C

1vyu – rVDCC beta 3

1vyv - rVDCC beta 4

1t3l - raVDCC beta 2+alpha 1S – rabbit

1t3s - raVDCC beta 2

2d46 – hVDCC beta 4a – NMR

3dve, 3dvj, 3dvk, 3dvm, 3g43 - rCav2.2 alpha 1B subunit+hCalmodulin

3oxq - hCav2.1 alpha 1C subunit IQ domain+hCalmodulin

1hvd, 1hve, 1hvf, 1hvg – hAnnexin V (mutant)

NH4+ channel
2nmr, 2nop, 2now, 2npc, 2npd, 2npe, 2npj, 2npg, 2npk, 1u77, 1u7c, 1u7g, 1xqe, 1xqf – EcAmCh – Escherichia coli

2b2h, 2b2i, 2b2j – AmCh – Archaeglobus fulgidus

3b9w, 3b9y – AmCh – Nitrosomonas europaea

MscL and MscS
3hzq – MscL – Staphylococcus aureus

2oar – MscL – Mycobacterium tuberculosis

2oau, 2vv5 - EcMscS

Chloride channel
2ahe, 2d2z – hClCh protein 4

1rk4 - hClCh protein 1

3o3t, 3p8w, 3p90, 1k0o - hClCh protein 1 (mutant)

Anion Channel
2jk4 – hVDAC

Ligand-gated ion channel
2vl0 – LGIC – Erwinia chrysanthemi

2xq3, 2xq4, 2xq5, 2xq6, 2xq7, 2xqa, 2xq8 – GvLGIC+inhibitor – Gloeobacter violaceus

3eam, 3ehz – GvLGIC

3igq – GvLGIC N-terminal

2xq9 – GvLGIC (mutant)+inhibitor

3lsv – GvLGIC (mutant)

Cyclic Nucleotide-Gated channel
3etq, 3ffq – mCNGC C-terminal

2zd9, 3beh - MlCNGC

Acid sensitive ion channel
3hgc, 3ij4 – ASC – chicken

ATP-Gated channel (AGC)
3h9v, 3i5d – AGC – Zebra fish

Proton channel
2kih, 2kwx – IVproton channel – Influenza virus

2kj1, 2l0j - IVproton channel – NMR

Voltage-gated hydrogen channel (VGHC)
3a2a – hVGHC C-terminal - NMR